Discrimination of Chiral Guests by Chiral Channels: Variable Temperature Studies by SXRD and Solid State 13C NMR of the Deoxycholic Acid Complexes of Camphorquinone and Endo-3-Bromocamphor
3a,12a-Dihydroxy-5b-cholan-24-oic acid (deoxycholic acid DCA) is able to discriminate between the R- and S-enantiomers of camphorquinone and endo-(1)-3-bromocamphor and select only the S-enantiomers from a racemic mixture. DCA forms novel well ordered 1:1 adducts with (1S)-(1)-camphorquinone and (1S...
| मुख्य लेखकों: | , , , , |
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| स्वरूप: | लेख |
| भाषा: | English English |
| प्रकाशित: |
Wiley-Blackwell
2008
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| ऑनलाइन पहुंच: | http://psasir.upm.edu.my/id/eprint/5809/1/Discrimination%20of%20Chiral%20Guests%20by%20Chiral%20Channels.pdf |
| सारांश: | 3a,12a-Dihydroxy-5b-cholan-24-oic acid (deoxycholic acid DCA) is able to discriminate between the R- and S-enantiomers of camphorquinone and endo-(1)-3-bromocamphor and select only the S-enantiomers from a racemic mixture. DCA forms novel well ordered 1:1 adducts with (1S)-(1)-camphorquinone and (1S)-endo-(-)-3-bromocamphor,
both of which have been characterized by single crystal X-ray diffraction SXRD). When DCA is cocrystallized with (RS)-camphorquinone and (RS)-endo-3-bromocamphor,1:1 adducts of the S-enantiomers are produced together with crystals of the
free racemic guest. In contrast, in the absence of (1S)-(1)-camphorquinone, DCA forms a 2:1 adduct with (1R)-(2)-camphorquinone. In this 2:1 adduct the guest is disordered
at ambient temperature and undergoes a phase change in the region 160–130 K similar to that observed for the ferrocene adduct, but with only partial ordering of the guest.
The SXRD structure of the low temperature form and the variable temperature 13C CP/MAS NMR are reported. Cocrystallizing DCA with (1R)-endo-(1)-3-bromocamphor gives
the free guest and a glassy solid. |
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